This one is a more obvious symbol fortunately. The text based faces he can't see at all, but he knows what a skull looks like. It does take him a second or two for it to sink in, but then he looks properly grim.

"I thought so," he murmurs, glancing up towards the entrance to the cave. He sighs softly, trying to keep his thoughts organized. Today is important. "I'm glad you checked up on me."